Quickie Questions - Earth - Gravity/Magnetism

is there a specific number for the earths magnetic field and can you repell a magnet using the opposite number of the magnetic field's number?

The average magnetic field strength of the Earth is 50 µT = 0.5 Gauss.

December 21, 2009

Kumar (Maharashtra/India)

If earth acts as a magnet then what is the directions of two poles?

The magnetic poles of our planet are reversed respect to the geographic poles, the South Magnetic Pole is near the North Geographic Pole, and the South Magnetic Pole is near the North Geographic Pole.

September 30, 2009

flubbyhead (usa)

Is my magnet mis-labeled, or is the North pole mis-labeled?

Because the magnetic poles of our planet are inverted respect to the geographical poles, the north side of your magnet will point to the north geographical pole, which corresponds to the south magnetic pole.

July 16, 2009

Ihsanullah (Pakistan)

If we travel around earth what happens to the earth's magnetic field comment.

The earth'a magnetic field is similar to a dipole magnetic field, but deformed by the action of the solar wind. It is continuosly changing and sometimes is extremely dynamic (geomagnetic storm). The magnetic field components have latitudinal and longitudinal dependencies. This page offers more information on this topic. Also, use our Earth's Magnetic Field interactive for a visualizacion.

May 18, 2009

Wendy (Florida)

What is the magnetic field of the Earth in Orlando, Florida?

The intensity and direction of the magntic field in a given location is not constant. Earth's magnetic field is always changing, and sometimes this changes can be significant, like whend there is a magneto-ionospheric storm. Now, if what you want to know is the inclination of the magnetic field in Orlando, it is about 60o.

May 18, 2009

tyson (australia)

what would happen if earth's core stopped moving?

One of the effects that I can think of immediately is the deformation or weakening of the Earth's magnetic field.

August 25, 2008

Brent (California United states)

do man made eletromagndic fields interfer with earths natural magnedic field ?

Earth's magnetic field is actually weak, varying from less than 0.3 gauss in most of South America and South Africa, to over 0.6 gauss around the magnetic poles. In comparison, a small iron magnet is about 100 gauss, a small Neodymium-iron-boron (NIB) magnet is about 2 000 gauss, and a big electromagnet is about 15 000 gauss. However, let's keep in mind that Earth's magnetic field also has an effect over other artificial or natural magnetic fields on our planet.

February 15, 2008

Ady (Medan/Indonesia)

What is the main cause of the earth's magnetic field?is it because the relativity effect of the differential rate of rotation of molten iron inside it?

In the Earth, the liquid metal in the outer core passes through a magnetic field, which causes an electric current to flow within the liquid metal. The electric current, in turn, creates its own magnetic field—one that is stronger than the field that created it in the first place. As liquid metal passes through the stronger field, more current flows, which increases the field still further. This self-sustaining loop is known as the geomagnetic dynamo. Energy is needed to keep the dynamo running. This energy comes from the release of heat from the surface of the solid inner core.
Adapted from PBS-NOVA.

December 17, 2007

If every mass pulls on every other mass, why then are people and its objects on Earth not pulled together?"

We are, and it is called gravity. We are not able to perceive the attraction among other objects on the surface of our planet because the attraction of Earth significantly surpasses any other.

July 23, 2007

Martin (CA)

I know the earth creates it's magnetic field by the iron molten core rotating. But how exactly does the molten core rotate? And are there any other forces(beside the iron molten core rotating)causing the earth to create is magnetic field?

The basic mechanism of magnetic field generation is generally accepted: a dynamo process, in which the magnetic field is maintained by convection of the highly electrically conducting fluid of the molten core. But the details are less clear. Recently (see, for example, this article), some details have been explained.

July 20, 2007

johanna (new zealand)

How would the reversal of the earths magnetic field affect bird (and other animals) migrations as they navagate useing its polarity and force?

Although this is an open topic, there is no firm evidence that the many magnetic field reversals that have taken place throughout our planet's history have coincided with or triggered extinctions. Reversals take hundreds if not thousands of years to complete, and because for any one type of animal that represents hundreds or thousands of generations, species have time to accommodate to the change. Moreover, even if the main dipole field were to collapse—an event that can last for up to 10,000 years during a reversal—residual fields 5 or 10 percent as strong as the main field would remain on the surface, and animals would be able to use those quite well for migration.
Extracted from NOVA.

April 13, 2007

Pattie (teacher) (Missouri/USA)

from one of my children: How did gravity get inside the Earth?

Actually, gravity didn't get inside our planet. Gravity is a natural force, inherent to all bodies, and is a function of the mass and the distance. The gravity of smaller bodies or far away bodies is very low, but exists.

Well, my brother said that there is no gravity in space. I was wondering if this is true or instead of nogravity, there's just micro gravity, because what keeps satllites etc. from flying off into space?

Hi Elizabeth - Good question! There certainly is gravity in space - it's just not as strong as it is on Earth. The force of gravity exists between any two masses, and depends on how massive they are are how far apart they are. The force of gravity is strong close to Earth (or near any other massive body, such as the Sun or other planets), but gets weaker as you go out in space.
Gravity is the force that keeps the relatively tiny mass of a satellite from leaving the orbit of Earth. See this page for lots of information about satellites, orbits, and gravity.
Thanks for this good question!

April 24, 2001

Tony (Florida, USA)

How is Earth like a magnet?

The conditions in the interior of the Earth actually create a magnetic field. So, it's like the Earth has a bar magnet inside of it, creating a magnetic field. The magnetic field of the Earth is surrounded by the magnetosphere.

July 26, 2000

Gavora (Kentucky)

I know that when something orbits the Earth, it stays in line with its orbit around the Earth. Was causes this to happen? What is it?

Objects, such as the Moon, travel at a speed that combats the pull of Earth's gravity. The closer an object is to Earth, the faster it must travel in order to stay in orbit.

This is similar to a ball on a string. You have to make the ball swing at a certain speed so that it stays in a circle. Otherwise, it will fall towards your hand!

July 19, 2000

Bill (MA, USA )

I would like to know what the 'Van Allen Radiation Belts' are. What makes the 'VARB' so important?

Van Allen Radiation Belts surround Earth and other planets. They are made of charged particles and are named after James Van Allen. Van Allen was in charge of the Explorer 1 satellite, which discovered the belts in 1958.

These belts are formed by trapped charged particles. The magnetic field traps these particles from the Sun. They then spiral around the lines of the Earth's magnetic field, going back and forth between magnetic poles.

These radiation belts are dangerous to astronauts. Shuttle missions are planned to stay away from the harmful particles as much as possible.

June 23, 2000

Heidi (Idaho, USA )

What is Gravity?

Gravity is the pull that one object exerts on another. The more mass the object has, the more pull it exerts. The Sun is so big, it pulls all the planets into orbit around itself. The Earth is so big, it pulls you down so you don't float away. But you exert a tiny pull on the Earth too! That's gravity.

February 4, 1999

Bri

Why do clouds float? Why don't they just fall to Earth? Everything clouds are made of falls to Earth. Why not clouds?

Clouds are made of very
tiny particles of water and ice. They form when water vapor condenses on
dust particles in the atmosphere. These cloud droplets are so small that
gravity can't pull them down. The droplets can combine together to form
rain drops. The rain drops are what fall to the ground; they are so big
that gravity can pull them down.

October 28, 1998

Nick (Colorado, USA)

I have read that the Earth's magnetic field is diminishing. Is this true, and if so, what would cause this to happen?

In most places in the world, the Earth's magnetic field has decreased
over the last century. It is impossible to predict fluxuations in the
Earth's magnetic field for the distant future. Magnetic reversals occur
(relatively) quickly, in Earth-time...
only tens of thousands of years or so. They occur about every 500,000 years or so. A polar reversal period may be coming up, but won't occur for several thousand years. When it does occur, it will take some time for the magnetic field to drop completely t
o zero. However, when it does, animals who rely on the Earth's magnetic field to navigate will have trouble. Human electonic communications and other electronic devices will also probably malfunction.

April 16, 1998

Kevin (England)

Can magnetic anomalies under the sea be detected by satellites in space?

Yes, magnetic anomalies are dectable and have been detected by satellite. The sattelite that collected this data is called MAGSAT.

March 13, 1998

Nasser (Oregon, USA)

At what earth rotational speed we will be thrown off into space, i.e. gravity can't keep us here on earth.

In order to throw us off the Earth at the equator, that is, to completely overcome the effects of gravity there, the Earth would have to rotate 806.4 times every day.

March 5, 1998

Rob (Arizona, USA)

When will the Earth's magnetic poles change? What will happen when it does? Will it happen fast or slow?

Magnetic reversals occur (relatively) quickly, in Earth-time...only tens of thousands of years or so. They occur about every 500,000 years or so. A polar reversal period is coming up, but won't occur for several thousand years. When it does occur, it will take some time for the magnetic field to drop completely to zero. However, when it does, animals who rely on the Earth's magnetic field to navigate will have trouble. Human electonic communications and other electronic devices will also probably malfunction.

February 20, 1998

Jessika (Connecticut, USA)

What would MOST LIKELY happen to the Earth's gravity if it were a cube instead of a sphere, assuming it would have the same rotation and distance from the moon and sun?

Over all, gravity is not at all related to the shape of the object, so the total gravity of the Earth would be the same. This means that if you were not standing on the Earth, you would feel the same pull from the Earth. However, gravity does depend on the distance from the center of the object. Since the distance from the center of the Earth would be greater toward the corners of the cube, the gravity would be less. In the center of the sides of the cube, the distance from the center would be less, and the pull of gravity stronger.

February 12, 1998

Alberto (Spain)

Could you tell me anything about the North Atlantic Anomaly in the Earth's magnetosphere?

The Earth's magnetosphere has regions of unusually high radiation. These regions are called the Van Allen Belts. You can think of them (in a loose sense!) as concentric rings of trapped radiation. Because of the way that the Earth's magnetic field is offset from its rotational axis, the Van Allen Radiation Belts come closest to the Earth's surface over the South Altantic ocean. This area is referred to as the South Atlantic Anomaly (SAA). Astronauts/Cosmonauts in spacecraft try to avoid this area of the magnetosphere because radiation is so intense. Anyhow, you'd think there would be a corresponding anomaly (area of intense radiation) in the Northern hemisphere...but because of the offset of the magnetic axis with respect to the rotational axis, there is no symmetry involved.

January 30, 1998

Lacey (Iowa, USA)

When you spin in circles, you can't seem to keep your arms to the side of your body. So why don't we float off the Earth into space since it is spinning too?

The spinning of the Earth is not actually what causes us to stick to it. Gravity is the attractive force that keeps us from flying off into space. This attraction is present between all things which have mass. Since the mass of your body and arms is small (compared to astronomical objects), you don't notice this attraction. However, since the Earth is so huge compared to your body, it attracts you very strongly. This is why we are not little satellites orbiting Earth!

January 27, 1998

Rob (New York, USA)

Were the Earth to experience a reversal of its magnetic field today, would fossil-fueled AC generators and electric motors still function?

Yes. In general, fossil-fueled AC generators and electric motors function without much interaction with the large-scale, external magnetic field of the Earth. In other words, the battery generates its own electromagnetic field, which runs the motor. As long as the battery doesn't die, there is no effect on the motor.A reversal to the Earth's magnetic field would have a big effect on radio communications, because such a reversal would affect the size of the atmosphere/ionosphere & the size & location of atmospheric currents. It would, of course, also affect navigation (from airplanes to birds!).